The effects of food and temperature regimes on life-history responses to fish kairomones in Daphnia hyalina x galeata

Abstract

Life-history responses to two concentrations of fish released info-chemicals at two temperature and food regimes were investigated for one clone of Daphnia hyalina x galeata. The presence of fish kairomones had a negative impact on size at maturity, carbon allocation to individual eggs and size of neonates in all treatments. Food concentration and temperature had positive effects on size of adult stages, independent of kairomone treatment. However, kairomone treatment were not found to interact with food or temperature. Age at maturity was positively influenced by increased temperature and food concentrations, whereas no direct kairomone effects were detected for this trait. Clutch size was not directly influenced by kairomone treatment, whereas both food concentration and temperature had strong, positive effects. [KEYWORDS: life-history, trade-offs, kairomones, Daphnia, food, temperature]